1. Field of the Invention
The present invention relates to a monitoring camera, and more particularly to a monitoring camera with a far infrared capability that has an enlarged field of view and increased visual distance.
2. Description of Related Art
Often, monitoring cameras are mounted in a fixed position at a high place in or on buildings or street corners to provide recordings of a specific location for security purposes or to document accidents. Monitoring cameras used in dark locations usually have a far infrared capability. With reference to FIGS. 5 and 6, a conventional monitoring camera with a far infrared capability comprises a cylindrical body (60), a lens cover (80) and a luminous body (70).
The cylindrical body (60) is hollow and has a longitudinal axis (not numbered), a front end (62) and a telephoto lens (61). The front end (62) has a threaded outer periphery and an inner periphery with an shallow dent (63). The telephoto lens (61) is circular and is attached to the front end (62) concentrically at the longitudinal axis.
The luminous body (70) has an annular circuit board (71) and multiple far infrared light emitting diodes (LEDs) (72). The annular circuit board (71) has a front surface (not numbered) and a rear surface (not shown) and is mounted in the shallow dent (63) of the cylindrical body (60). The LEDs (72) are mounted on the front surface of the annular circuit board (71).
The lens cover (80) has a threaded inner periphery (not numbered) and screws onto the outer threaded periphery of the cylindrical body (60) to enclose the luminous body (70) between the lens cover (80) and the cylindrical body (60) and to protect the telephoto lens (61).
However, the conventional monitoring camera has the following disadvantages.
1. The cylindrical body (60) and the lens cover (80) have the same diameter, and the number of the far infrared LEDs (72) mounted on the annular circuit board (71) is limited by the diameter of the cylindrical body (60). Therefore, the visual distance of the monitoring camera is limited by the intensity of the limited number of LEDs (72).
2. The lens cover (80) has the same diameter as the cylindrical body (60), which limits the aperture of the lens cover (80). Therefore, the monitoring camera has a limited field of view because the aperture of the lens cover (80) cannot be increased to provide more space for the telephoto lens (61).
3. The lens cover (80) has a long threaded inner periphery to directly mount the lens cover (80) on the cylindrical body (60) and enclose the luminous body (70) between the cylindrical body (60) and the lens cover (80). Therefore, the lens cover (80) is troublesome to detach from the cylindrical body (60) and easy bumps inadvertently against the LEDs (72) when being detached.
The present invention has arisen to mitigate or obviate the disadvantages of the conventional monitoring camera with far infrared.